A Note on National and County Car Ownership Projections in Ireland

I N recent years Irish transportation problems have attracted considerable public interest and controversy. The principal reason for this has been the rapid rise in car ownership levels which expresses itself most clearly in high density metropolitan areas where the problem of urban traffic congestion—particularly in the Dublin conurbation—has attained critical proportions. In addition, the Household Budget Inquiry 1965-^66 [1] which investigated the expenditure patterns of urban households, showed that transportexpenditure has increased more rapidly than spending on any other category since the last Inquiry in 1951-52 [ 2 ] : it has expanded from 4-39 per cent of household expenditure in 1951—52 to 9-59 per cent in 1965-66. There has been speculation about the impact of transport demand upon the capacity, of transport networks and the question of how this demand can be satisfied at minimum cost to the community: that is taking account of social costs and benefits. The number of private cars in Ireland increased from 52,000 i m i 9 4 7 t o 135,000 in 1957 and 314,000 in 1967. In terms of cars per capita ownership has increased from 0-618 in 1947 to 0-047 m 1957 and 0-169 in 1967. Blackwell [3] fitted an exponential trend to the time series data. The trend is of the form: > • , (